I started to install a new canvas top and have a question. It seems that there must be a part missing or i am missing something. The material rolls over the forward edge of the top but, there is now way to mechanically fasten it to the framework (see picture below). It seems that it needs to be stapled or clipped in some manner.

The material needs to be trimmed and there is a rubber gasket that covers the gap. Is there something I am missing or does it just get glued in place?

Yep, just glued on.
Lower the top frame on the oblong mounting holes before starting. Stretch the top over the frame and tape it to the windshield when it's wrinkle free. Then pull the side flaps down and secure on the Velcro in the door jamb. Adjust height of frame to fit the top around the side window.
If the fabric is short behind the window at the flaps now, remove the top and throw it away. If it looks good so far, pull any final wrinkles out and mark the fold over the windshield header with chalk.
If the corner pockets are too long and have to be folded over the header, they will be too thick to fold neatly. Carefully remove the stitching and cut out the excess fabric.
Now it's finally time to use the contact adhesive and glue the front on to the header.
If all is well and everything fits, let us know the brand since there are lots of ill fitting tops made from patterns taken from old shrunken vinyl tops.
Kurt

Did a new top install myself a few months ago. I installed a plain Robbins vinyl top, so I don't know if the proper adhesive would be any different, but.... I used Weldwood Contact Cement, which was recommended to me my a very good local upholstery shop. The stuff worked great and the top fits well. I also added a new rubber weather strip on top for the frame. The Club Store/Delta sells that strip and it was also a good fit and works great. Good luck!